Category: 04. Autacoids And Their Antagonists

They were named so because of their presumed origin from the prostate gland. Human seminal fluid is the richest known source, but they are also present in various tissues. The prostaglandins are synthesized from polyunsaturated fatty acids at their sites of action. PG E2 and PG F2 are the two main prostaglandins. They are released…

It is widely distributed in plants and animals. Highest concentration in mammals is found in the pineal gland, acting as a precursor for melatonin. It is synthesized from the amino acid tryptophan and acts on several types of receptors. Pharmacolocial Actions: HT causes constriction of renal, splanchnic, meningeal, and pulmonary arteries and veins and venules,…

Allergic Disorders:- Including urticaria, seasonal hay fever, atopic and contact dermatitis, mild blood transfusion reactions. N.B. Their topical use is not recommended because of the risk of sensitization and a high tendency to cause eczematous reactions. They are not effective in bronchial asthma and common cold. Other uses: Diphehydramine and promethazine are used as hypnotics.…

Antihistaminic Actions:-they block histamine effects at various sites. Other Effects: are independent of the antihistaminic effects and vary widely according to the drug used. Most of them produce CNS depression resulting in sedation, drowsiness, inability to concentrate, and disturbances of coordination. But very few agents such as phenindamine may produce stimulation.Anti-motion sickness effects are exhibited…

Exposure to the offending agent should be terminated. Adrenaline has actions opposite to those of histamine and thus acts as a physiological antagonist. It may be given by SC or IM route. Hypotension should be corrected with the infusion of intravenous fluids. Corticosteroids are occasionally used. Other supportive measures include administration of oxygen and artificial…

Cardiovascular system Histamine produces dilatation of capillaries and venules accompanied by a fall in blood pressure. The mechanism is direct relaxation of the smooth muscles of blood vessels. This effect cannot be adequately reversed by antihistaminic agents but by adrenaline. It also has positive inotropic and chronotropic actions on the heart, impairs AV conduction, and…

It is a potent tissue amine widely distributed in plant and animal tissues and in the venoms of bees. In man, it is formed by decarboxylation of histidine and major portion is stored in mast cells and basophils. Mechanisms of Action: It acts on 2 major types of receptors Stimulation of H1 receptors results in…

“Autacoids” (Greek “self-remedy”) is a collective term for various endogenous peptides, prostaglandins, leukotrienes, and cytokines. These are sometimes also called local hormones. They play important roles in physiologic processes and also have several pharmacological significances.